#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) {
        vector<vector<int>> ret;
        sort(nums.begin(), nums.end());

        int n = nums.size();
        for (int i = 0; i < n; ) {
            if (nums[i] > 0) break;
            int left = i + 1, right = n - 1, target = -nums[i];
            while (left < right) {
                int sum = nums[left] + nums[right];
                if (sum > target) right--;
                else if (sum < target) left++;
                else
                {
                    ret.push_back({ nums[left], nums[right], nums[i] });
                    left++, right--;
                    while (left < right && nums[left] == nums[left - 1])  left++;
                    while (left < right && nums[right] == nums[right + 1])  right--;
                }
            }

            i++;
            while (i < n && nums[i - 1] == nums[i]) i++;
        }

        return ret;
    }
};